Arm chair



FIG. 1 is a top front perspective view of an arm chair showing my new design;

FIG. 2 is a front perspective view thereof;

FIG. 3 is a side perspective view thereof;

FIG. 4 is a rear perspective view thereof;

FIG. 5 is a top perspective view thereof; and

FIG. 6 is a bottom perspective view thereof. 

The ornamental design for an arm chair, as shown and described. 